QUANTIFYING ARSENIC RELEASE FROM MINERALS TO WATER: THEORY VS. PRACTICE

Arsenic (As) and other toxic trace elements are released from minerals as a result of biogeochemical reactions, which can be sensitive to changes in redox, pH, and temperature, as well as microbial activity. Modeling As release from minerals to water requires information on rates. For this talk, I will discuss methods for translating laboratory-derived rates of As release to “model-friendly” rates, and will describe field studies of As release under different biogeochemical conditions to compare what we predict from theory with what we observe in the field. One particularly challenging process to model is As release associated with Fe reduction, which is responsible for As contamination of groundwater in many regions worldwide. This mechanism is complicated not only by microbial processes, but also complex interactions between As and Fe minerals.